A MEMS-fluxgate-based sensing system for the detection of Dynabeads

In this paper, a microfluxgate sensor was introduced into the application of magnetic bead detection. Micro-electro-mechanical systems (MEMS) technology was used to realize the microfluxgate sensor. Making use of the superparamagnetic property that micron-sized magnetic beads can be magnetized in a magnetic field, a magnetic bead detection system based on this microfluxgate sensor was designed and established. Dynabeads obtained by purchase were diluted to different concentrations to characterize the detection performance of the system. Experimental results show that by applying a dc magnetic field in the range of 0.54 to 1.05 mT, Dynabeads with a concentration as low as 9000 beads ml^–1 can be detected by the system. Furthermore, from the results, each sample can be clearly distinguished from the others, which prove that the detection system has the ability to make rough estimates to the concentrations of Dynabeads. The MEMS-fluxgate-based detection system possesses many advantages, such as a low minimum detectable limit, small size, light weight and compatibility with microelectronic technology. Moreover, a MEMS microfluxgate sensor can be made into an array for the synchronous detection of multi-target biomolecules and is very suitable for integration with interface circuits. (paper)